Can I get sued for malfunctioned (free) software?

So, I created a small financial trading bot I want to distribute for free. Basically the user downloads the program, enters their API keys and based on an interface the user can make trades more automatically. The software is free in the sense that I do not charge any money for the program.

Could users sue me if the bot behaves incorrectly? E.g. it performs unwanted trades, the API keys get exposed, etc.
I guess when I do not charge money they cannot sue me? Does this change when I would charge money for it?